JP4865891B1 - Optical fiber, optical fiber ribbon and optical fiber cable - Google Patents

Abstract

An optical fiber, an optical fiber ribbon, and an optical fiber cable that reduce an increase in transmission loss and reduce a decrease in strength are provided.
In an optical fiber strand in which a primary coating layer is coated on an outer peripheral surface of an optical fiber, the primary coating layer includes an ultraviolet curable resin, and the ultraviolet curable resin includes a reactive silane coupling agent. Provided is an optical fiber that includes 0.05 part by mass or more and 0.75 part by mass or less and includes a non-reactive silane coupling agent by 0.05 part by mass or more and 0.75 part by mass or less.
[Selection] Figure 1A

Description

  The present invention relates to an optical fiber suitable for constituting an optical fiber cable accommodated in a housing such as a slot rod, and an optical fiber ribbon and an optical fiber cable using the same.

  An optical fiber has a structure in which an optical fiber body is covered with a resin or the like, and has a high breaking strength immediately after manufacture. In general, an optical fiber having an outer diameter of 250 μm made of a soft primary coating layer and a hard secondary coating layer on a glass fiber or plastic fiber made of a core and a cladding is used.

  Optical fiber strands are required to maintain the initial high breaking strength when used for a long time under various usage conditions. In particular, in an environment where an actual optical fiber is laid, durability is required to maintain the light transmission characteristics and the initial breaking strength of the fiber over a long period of time. In particular, durability in a warm water atmosphere and optical fiber durability in a high temperature and high humidity atmosphere are strongly demanded.

  Optical fiber cables with a capacity of more than 1000 cores are laid and operated. However, as the number of subscribers who use lines further increases, it is necessary to add them. The pipe line for laying the optical fiber cable is expected to reach its limit, and it is necessary to increase the diameter and density of the optical fiber cable.

  The slot type optical fiber cable has an optical fiber ribbon (hereinafter abbreviated as “tape core”) in a plurality of spiral slot grooves (housing bodies) formed on the outer peripheral surface of the slot rod. It is accommodated in a state where a plurality of sheets are stacked. The slot rod is a long body made of plastic such as polyethylene, and a tension member made of a metal stranded wire, a fiber reinforced plastic (FRP) rod or the like is provided at the center thereof. A tape winding layer in which a tape such as a polyester tape is wound is provided on the periphery of the slot rod, and a sheath layer made of polyethylene or the like is coated thereon.

  The tape core wire has a configuration in which a plurality of optical fiber strands are arranged in parallel and covered using a collective coating layer made of an ultraviolet curable resin or the like. When configuring the optical fiber cable, in order to increase the number of tape cores that can be accommodated in the slot rod, the thickness of the batch coating layer of the tape cores is reduced. When the fiber optic cable is reduced in diameter, the slot must be shallow and narrow.

  When the optical fiber cable having a reduced diameter is bent, the tape core wire is difficult to move freely in the slot and is fixed locally. Therefore, the portion of the optical fiber cable that has received a compressive force is buckled, and the tape core and the optical fiber are bent in a complicated manner. Further, when the optical fiber cable contracts in a low temperature condition, the side pressure from the slot wall surface increases, and the optical fiber strand located at the end of the tape core wire is compressed in the longitudinal direction. Therefore, in the case of an optical fiber made of glass, the fiber buckles and causes microbending, which increases transmission loss. Further, there is a problem that the glass fiber protrudes and the coating is removed, and the fiber strength is lowered. In particular, such a problem tends to occur when the number of optical fiber strands constituting the tape core wire is eight or more.

JP 2009-122209 A JP 2006-215445 A JP 2006-249264 A

  In Patent Document 1, in order to prevent an increase in transmission loss even when a small-diameter and high-density optical fiber cable is bent, the gap between the glass fiber and the coating of the optical fiber constituting the tape core is disclosed. It is disclosed that the stress relaxation start time is shortened to 1.5 minutes or less when a pulling force of 0.3 N / mm is applied. Patent Document 2 discloses that 0.1 mass part of a low molecular weight (non-reactive) silane coupling agent is added to an ultraviolet curable resin of a primary coating layer of an optical fiber in order to suppress a decrease in optical fiber strength. In the above, what contains 3.0 mass parts or less is disclosed. Patent Document 3 provides a liquid curable resin composition having high fiber strength, 0.1 to 10% by mass of an alkoxysilane compound having no radically polymerizable functional group, and 0.01 to 1% by mass of a hindered amine compound. The thing containing is disclosed.

  However, none of the patent documents teaches an optical fiber that reduces both an increase in transmission loss and a decrease in strength while ensuring long-term use reliability. As will be described later, if a relatively large amount of a non-reactive silane coupling agent is blended in the optical fiber, there is a problem that an increase in transmission loss due to bending of the optical fiber cable after cable formation becomes large. .

  The present invention provides an optical fiber, a tape core, and an optical fiber cable that ensure long-term use reliability and reduce both increase in transmission loss and decrease in strength.

  In an optical fiber strand in which a primary coating layer is coated on an outer peripheral surface of an optical fiber, the primary coating layer contains a resin, and the resin contains a reactive silane coupling agent in an amount of 0.05 parts by mass or more and 0.75. Provided is an optical fiber which contains 0.05 parts by mass or more and 0.75 parts by mass or less of a non-reactive silane coupling agent.

  The optical fiber of the present invention ensures long-term reliability of use, and can reduce transmission loss even when a thin and high-density optical fiber, tape core, and optical fiber cable are bent. It is possible to reduce both an increase and a decrease in strength.

It is a schematic sectional drawing which shows the multi-core (400 core) optical fiber cable which concerns on one Embodiment of this invention. It is a schematic sectional drawing which shows the multi-core (1000 core) optical fiber cable which concerns on one Embodiment of this invention. It is a schematic sectional drawing which shows the tape core wire which concerns on one Embodiment of this invention. It is a schematic sectional drawing which shows the optical fiber strand which concerns on one Embodiment of this invention. It is the schematic of the sample for a drawing test which concerns on one Embodiment of this invention. It is a graph which shows the example of the transmission loss increase in the heat cycle test of an optical fiber cable. In one embodiment of the present invention, the maximum amount of increase in transmission loss when the addition amount of the reactive silane coupling agent is fixed and the addition amount of the non-reactive silane coupling agent is changed, and after ZSA (zero stress aging) It is the figure which plotted the value of 15% of fiber breaking strength of 15%.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings described below, components having the same function are denoted by the same reference numerals, and repeated description thereof is omitted.

  1A and 1B show a schematic cross section of a multi-core optical fiber cable 1 according to an embodiment of the present invention. The multi-core optical fiber cable 1 includes a plurality of tape core wires 2 disposed in a slot, a slot rod 3 having a plurality of slot grooves (accommodating bodies) for housing the plurality of tape core wires 2, and a center of the slot rod 3. A tension member 4, a sheath layer 5, and a pressing tape winding layer 6 are included.

  FIG. 2 shows a schematic cross section of a tape core wire 2 according to an embodiment of the present invention. The tape core wire 2 includes a plurality (8 in this example) of optical fiber strands 2-1 and a collective coating layer 2-2 covering the same.

  FIG. 3 shows a schematic cross section of an optical fiber according to an embodiment of the present invention. In this example, an optical fiber body 2-1-1 having a diameter of 125 μm is covered with a primary soft coating layer 2-1-2 and further covered with a secondary hard coating layer 2-1-3.

  Here, the optical fiber according to an embodiment of the present invention may be for single mode transmission or for multimode transmission. There are no limitations on the material of the core and cladding of the optical fiber, and for example, a conventionally used material such as quartz can be used. The optical fiber of the present embodiment may be any material as long as it is a material normally used for an optical fiber, such as a glass optical fiber or a plastic optical fiber.

  The primary soft coating layer 2-1-2 of the present embodiment is a cured film obtained by adding a polyether urethane acrylate as an oligomer, and adding a monofunctional acrylate monomer and a vinyl monomer having different functional groups, and a photoinitiator. And an ultraviolet curable resin in which the adhesiveness to the glass fiber is adjusted by changing the amount of reactive and non-reactive silane coupling agents. That is, in this embodiment, the ultraviolet curable resin contained in the primary soft coating layer includes both a reactive silane coupling agent and a non-reactive silane coupling agent.

  The reactive silane coupling agent is a silane coupling agent incorporated into the skeleton of the ultraviolet curable resin contained in the primary soft coating layer, and includes, for example, γ-mercaptopropyltrimethoxysilane, γ-methacryloxypropyltrimethoxy. Although it is silane, it is not limited to this. The non-reactive silane coupling agent is a silane coupling agent having no radical polymerizable functional group, and is, for example, diethoxydimethylsilane. Here, the term “reactivity” refers to radical polymerization, but is not limited thereto.

  The secondary hard coating layer 2-1-3 includes an ultraviolet curable resin whose cured film has a Young's modulus of 550 to 850 MPa. In this embodiment, although not limited, the outer diameter of the primary coating is 185 to 195 μm, and the outer diameter of the secondary coating is about 245 μm.

  The Young's modulus of the optical fiber coating layer actually produced is affected by the manufacturing conditions. Therefore, a sheet (a film obtained by UV-curing a resin into a sheet) is not produced and measured, but is actually measured from an actually produced optical fiber.

  For the measurement of the pulling stress, for example, an optical fiber strand 2-1 cut to a length of about 200 mm is prepared. As shown in FIG. 4A, the coating is cut at a position of about 20 mm from the end portion to form the cut portion 9, and the glass fiber of the cut portion 9 is exposed. As shown in FIG. 4 (a), a part of the end portion 20 mm of the optical fiber is bonded and fixed to the end portion of the mount 7 obtained by cutting the sandpaper into a rectangle using an adhesive 8. At this time, the gap between the adhesive 8 and the notch 9 is set so that the adhesive 8 does not enter the notch 9. As the adhesive 8, a jelly-like Aron Alpha (registered trademark) (manufactured by Toagosei Co., Ltd.) that does not easily deform when cured is used.

  Then, as shown in FIG. 4B, the adhesive 8 and the optical fiber 2-1 are cut at a position 10 mm from the coating cut portion 9. One end of the mount 7 and the optical fiber 2-1 not bonded to the mount 7 is chucked with a tensile tester. The chucking distance between the coating cut 9 and the optical fiber 2-1 is 100 mm. By pulling the optical fiber 2-1 at a drawing speed of 5 mm / min in a state where the adhesive portion between the mount 7 and the optical fiber 2-1 is fixed, the portion from the adhesive portion indicated by the oblique lines in FIG. Pull the glass fiber and track the maximum stress. The results are shown in Table 1. The value of the pulling stress in Table 1 is an average value of the results of repeated measurement six times.

  For the measurement of the fiber breaking strength, for example, an optical fiber strand 2-1 cut to a length of about 2 m is prepared. Both ends of the optical fiber are respectively wound around a mandrel (φ100 mm) of a tensile test apparatus and fixed. The distance between both mandrels is 500 mm. Tensile speed 2.5% / min. Then, the optical fiber 2-1 is pulled and the breaking strength is measured. After the optical fiber was ZSA for 30 days at 85 ° C./85% RH, the breaking strength was measured in the same manner. Table 1 shows the results of 15% residual rate after ZSA. The value of ZSA in Table 1 is the fiber break strength 15% remaining rate [%] after ZSA.

  Four optical fiber strands of the above-described embodiment, each having a colored layer having a thickness of about 5 μm, were arranged in parallel, and a four-core tape core wire having a thickness of 320 μm and a width of 1.1 mm was produced by batch coating. This 4-fiber ribbon was immersed in warm water at 60 ° C., and 200 days later, the transmission loss of each fiber was measured at a wavelength of 1.55 μm. The results are shown in Table 1.

  Eight optical fiber cores having a thickness of 320 μm and a width of 2.10 mm were prepared by arranging eight optical fiber strands of the above embodiment, each having a colored layer having a thickness of about 5 μm, arranged in parallel. Using this 8-core ribbon, an S-type slot having five slot grooves with an outer diameter of 14.6 mm, a spiral pitch of grooves of 600 mm, and a depth of 4.0 mm as shown in FIG. 1A is used. A 400-core cable was manufactured. The number of laminated tape cores in each slot groove is ten.

  In this 400-core cable structure, the slot diameter is small, the groove depth is shallow, and the upper and lower spaces are 80 μm or less. Therefore, when the cable is bent, the tape core wire cannot move in the longitudinal direction due to friction. At the same time, the tape core is slackened inside the bend, the tape core is buckled because it hits the wall surface beyond its movable region (window), and the optical fiber is compressed in the longitudinal direction to cause microbending. As a result, transmission loss tends to increase.

  A length of 1000 m of the 400-core cable is wound on a drum having a body diameter of 1400 mm, put into a heat cycle tank, and subjected to a heat cycle test of -30 ° C to 70 ° C for 3 cycles. Transmission loss of each optical fiber in the 400-core cable Was measured at a wavelength of 1.55 μm. An example of a change in transmission loss is shown in FIG. In FIG. 5, a thick line indicates a change in temperature, and a thin line indicates a change in transmission loss.

  Only the optical fiber strands at both ends of the deepest tape core of each groove showed an increase in transmission loss. As in the example of FIG. 5, the transmission loss increases on the low and high temperature sides. The maximum transmission loss occurred when the temperature reached −30 ° C. in the first cycle. In subsequent cycles, the increase in transmission loss is relatively gradual. Table 1 shows the result of obtaining the maximum value of the transmission loss increase of the optical fiber.

＊非反応性： 非反応性シランカップリング剤添加量［質量部］
反応性： 反応性シランカップリング剤添加量［質量部］
引抜応力： 引抜応力［Ｎ］
伝送損失： 伝送損失増加最大値［dB/km］を波長1.55μｍで測定
ＺＳＡ： ＺＳＡ後のファイバ破断強度１５％残存率［％］
６０℃温水： ６０℃温水２００日後の伝送損失値［dB/km］波長1.55μｍで測定
判定： ◎十分に実用的な使用に耐えられる、○実用的な使用に耐えられる、×実用的な使用に好ましくない、の３段階で評価

* Non-reactive: Amount of non-reactive silane coupling agent added [parts by mass]
Reactivity: Reactive silane coupling agent addition amount [parts by mass]
Pull stress: Pull stress [N]
Transmission loss: Maximum increase in transmission loss [dB / km] measured at a wavelength of 1.55 μm ZSA: 15% fiber fracture strength remaining after ZSA [%]
60 ° C hot water: Transmission loss value [dB / km] 200 days after 60 ° C hot water measured at 1.55μm wavelength Judgment: ◎ Can withstand practical use, ○ Withstand practical use, × Practical use Evaluation in three levels

  As will be appreciated by those skilled in the art according to the present invention, in the long-term reliability of the use of optical fiber, the maximum increase in transmission loss and the transmission loss value after 200 days of 60 ° C. hot water increase the transmission loss of the optical fiber. It is a kind of index to be evaluated, and the pulling stress is also a kind of index of transmission loss because it shows the adhesion between the glass fiber of the optical fiber and the coating. Further, the value of the 15% residual ratio of the fiber breaking strength after ZSA is a kind of index for evaluating the strength reduction of the optical fiber.

  As will be understood by those skilled in the art according to the present invention, the value of the drawing stress [N] is preferably about 5 to 12 for practical use from the viewpoint of increasing the transmission loss of the optical fiber. The maximum value of transmission loss increase [dB / km] (measurement wavelength 1.55 μm) is preferably 0.1 or less for practical use. The value of 15% fiber residual strength [%] after ZSA is preferably 90 or more for practical use. And the value of the transmission loss value [dB / km] (measurement wavelength 1.55 μm) after 60 ° C. hot water immersion is preferably 0.1 or less for practical use.

  Comparative Example 1 is not preferred for practical use because the amount of non-reactive silane coupling agent added is 0 and the value of ZSA is relatively low at 80. Comparative Example 2 is not preferred for practical use because the amount of reactive silane coupling agent added is 0 and the value of 60 ° C. hot water is relatively large at 0.4. In Comparative Example 3, the addition amount of the reactive silane coupling agent is 1, and the maximum value of increase in transmission loss is relatively large at 0.14, which is not preferable for practical use. And the comparative example 4 is unpreferable about practical use since the addition amount of a non-reactive silane coupling agent is 1, and the transmission loss increase maximum value is comparatively large with 0.14.

  FIG. 6 shows various changes in the addition amount of the non-reactive silane coupling agent when the addition amount of the reactive silane coupling agent is 0.3 parts by mass, based on the values in Table 1 according to the present embodiment. FIG. 6 is a graph plotting the maximum value of increase in transmission loss and the value of 15% remaining rate of fiber breaking strength after ZSA when the values are set. From FIG. 6, when no non-reactive silane coupling agent is added, the maximum value of increase in transmission loss is as low as 0.03, but the value of 15% fiber breakage strength after ZSA is also low as 80, resulting in an increase in transmission loss. It is not possible to reduce both the strength reduction. When the addition amount of the non-reactive silane coupling agent is increased, the maximum value of increase in transmission loss is increased, and the value of 15% residual ratio of fiber break strength after ZSA tends to increase. Therefore, it is not possible to reduce both the increase in transmission loss and the decrease in strength only by changing the addition amount of the non-reactive silane coupling agent.

  As shown in Table 1, if the addition amount of the non-reactive silane coupling agent and the addition amount of the reactive silane coupling agent are not optimized, the increase in the maximum transmission loss is reduced and the strength reduction is reduced. I can't do it. In other words, the transmission loss of the optical fiber is increased by optimizing the amounts of the non-reactive silane coupling agent and the reactive silane coupling agent contained in the primary coating layer covering the optical fiber body according to the present embodiment. Both strength reduction and strength reduction can be reduced.

  As shown in Table 1, an optical fiber having an addition amount of the non-reactive silane coupling agent of 0.05 part by mass or more and 0.75 part by mass or less and a drawing stress of 5 N or more and 12 N or less (Example) 1-6), the maximum increase in transmission loss is 0.1 dB / km or less. Therefore, an embodiment including an addition amount of the non-reactive silane coupling agent of 0.05 part by mass or more and 0.75 part by mass or less is preferable for practical use.

  In the optical fiber strands according to Examples 1 to 4 including 0.5 parts by mass or less of the addition amount of the non-reactive silane coupling agent, the transmission loss increase maximum value is 0.07 dB / km or less. Therefore, more preferably, the addition amount of the non-reactive silane coupling agent is 0.05 parts by mass or more and 0.5 parts by mass or less.

  The optical fiber wires according to the present embodiment (Examples 1 to 6) have a fiber break strength 15% residual ratio after ZSA that is sufficiently large as 90% or more, in terms of reliability in long-term use of optical fibers. Withstand enough, practical use.

  Even when 0.05 to 0.75 parts by mass of the non-reactive silane coupling agent is contained, the optical fiber strand containing less than 0.05 parts by mass of the reactive silane coupling agent and having a drawing stress of less than 5N In (Comparative Example 2), the transmission loss value after 200 days of 60 ° C. warm water is as large as 0.4. From Table 1, the increase in transmission loss after 200 days of 60 ° C. hot water can be suppressed when the amount of reactive silane coupling agent added is 0.05 parts by mass or more.

  And even if it is a case where 0.05-0.75 mass part of non-reactive silane coupling agents are included, the addition amount of a reactive silane coupling agent is larger than 0.75 mass parts, and a drawing stress is larger than 12N. In the optical fiber (Comparative Example 3), the maximum increase in transmission loss is remarkably large at 0.14. Therefore, an increase in transmission loss can be suppressed by setting the addition amount of the reactive silane coupling agent to 0.75 parts by mass or less. Therefore, an embodiment including the addition amount of the reactive silane coupling agent is 0.05 parts by mass or more and 0.75 parts by mass or less is preferable for practical use.

  The present invention is not limited to the 400-core optical fiber cable of the above-described embodiment, but the 1000-core optical fiber cable shown in FIG. It can also be applied to fiber cables.

DESCRIPTION OF SYMBOLS 1 Optical fiber cable 2 Tape core wire 3 Slot rod 4 Tension member 5 Sheath layer 6 Holding tape winding layer 2-1 Optical fiber strand 2-2 Collective coating layer 2-1-1 Optical fiber main body 2-1-2 Primary Soft coating layer 2-1-3 Secondary hard coating layer

Claims (5)

In the optical fiber strand in which the primary coating layer is coated on the outer peripheral surface of the optical fiber,
The primary coating layer includes a resin,
The resin contains 0.05 part by mass or more and 0.75 part by mass or less of a reactive silane coupling agent and 0.05 part by mass or more and 0.75 part by mass or less of a non-reactive silane coupling agent. Characteristic optical fiber.   2. The optical fiber according to claim 1, wherein a stress when a drawing force of 50% / min is applied between the optical fiber and the primary coating layer is 5N or more and 12N or less. Strands.   2. The optical fiber according to claim 1, wherein the resin contains 0.05 part by mass or more and 0.5 part by mass or less of a non-reactive silane coupling agent. A plurality of the optical fiber strands according to any one of claims 1 to 3,
Each of the plurality of optical fiber strands is further coated with a secondary coating layer and a coloring layer,
The optical fiber ribbon is characterized in that the plurality of optical fiber strands are arranged in parallel and covered with a batch coating layer. An optical fiber ribbon according to claim 4,
An optical fiber cable comprising a housing for housing a plurality of the optical fiber ribbons in a stacked manner.

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